First off, I'd like to apologize for not phrasing the question in a way where I invited you to choose if you wanted to cut any of the spells, such as an Obelisk, for an additional land. I'll try to make sure that I leave all legal options open whenever I ask a question.

As for the lands, the important things to keep in mind about this deck's main colors are that you need to have access to both red and black mana early, for Goblin Deathraiders + Blightnings and you'll want to just generally make sure that you can play your spells. Many decks can get away with just one of their main colors for a bit, this one would have trouble if that happened.

So, we need lots of red and lots of black. Unfortunately, we still have two more colors to worry about.

Now, an easy trap to fall into with a deck like this would be to double count the blue-white sources. "I have two cards that need blue and two cards that need white, and I have an Obelisk of Bant and an Arcane Sanctum so I have two white sources and two blue sources and I don't need anything else! Great!" Don't do this!

Yes, you have two sources that give you white and you have two sources that give you blue, but those are condensed into two cards. You wouldn't want to play two sources for four splash cards of one color, so don't think about doing it if your splash cards are separated over two colors.

That leaves us with either two lands and an Obelisk of Jund or three lands to work with.

Now it is obviously appealing to run 17 lands, adding a Swamp, a Mountain, and an Island and just calling it a day. While this is quite close to being right, I believe that there are two better (though slightly uglier) ways that we can do things.

This was the way that Josh Ravitz constructed his mana base when he built this deck in the Top 8 of a Rochester, NY PTQ. This mana base obviously served him well, as he was able to walk away from the tournament with an invite to Pro Tour–Kyoto. Until a few hours ago, this was the mana base that I was going to recommend for this deck, but after a lot of painful thinking I decided that the mana base that I would go with is:

While I want my blue in a timely manner, if I don't draw red and black early, then I just don't think that I'm going to be able to win.

Honestly, the difference between these two mana bases is very small, and I'm not 100% sure that I'm right with my 17-land build. I give up a blue source in exchange for a slightly better chance of getting my base colors fast.

Cycling

Cycling allows you to play specialized cards that you probably wouldn't want otherwise.

Fog can be one of the most devastating cards to see in a Limited game. One moment you're attacking for lethal damage, safe in the knowledge that your opponent would need to kill and/or bounce three of your creatures in order to survive to the next turn. You're feeling great and already considering whether you have anything in your sideboard that will make the next game or two even easier for you.

Aaaaand the next moment you have your head in your hands while your opponent is attacking you for the game, wondering if there was any way you could have tried to play around a silly little instant that prevents all combat damage.

Now under normal circumstances, Fog effects usually just aren't worth playing. While having a Fog will allow you to steal wins in otherwise very close games, those types of games are typically outnumbered by the times where drawing a card that does nothing to affect the board will be a great step on the road to a loss.

When you tack on the ability to cycle your Fog, then suddenly you don't have to feel guilty about playing the sneaky little instant.

Angelsong is not a great card, but it's something that a lot of people have and will continue to play, so it is worth considering before you go in for that lethal attack. Now, don't let a fear of Fog stop you from making the right play(s) that will allow you to kill your opponent. But if you're playing Shards Limited, your opponent has Angelsong mana open, and you have a safe enough lead that you can play in such a way that you will still win that turn or the next turn and you won't lose if your opponent has the Angelsong, then you might want to seriously consider that course of action.

Of course, if you try to play around a non-existent Angelsong and your opponent topdecks a Predator Dragon to kill you, you're going to feel awfully silly.

Now considerably more than half the time that I draw an Angelsong, I'm going to cycle it. But when I do play it, it's often going to singlehandedly win the game for me. And that's perfectly fine by me,

Cycling is a great ability to put onto a Fog effect, and just the existence of this one little instant makes the final turn(s) in Shards of Alara Limited a lot more interesting than they might be otherwise. But how do the 12 other cycling cards in Shards of Alara shape up?

Unleash the (Plow) Beast! Or Not....

Yoked Plowbeast, Ridge Rannet, and Jungle Weaver all benefit immensely from being able to cycle. Pretty much any time I'm building a deck that has 17+ mana sources, I wish that I could have another fatty in my deck. Unfortunately, because of mana curve considerations, I'm usually unable to make room for that six- or seven-mana monster.

Of course, when that 5/5 (or 6/4, or 5/6) has cycling, then I don't have to worry about it clogging up my hand while the game gradually slips away from me.

I will be happy to play any of these seven-cost creatures in my deck, but of course I'm happiest if I have Jungle Weaver. I'd play the 5/6 reach monster quite a bit even if it didn't have cycling. There are very few creatures that can attack past Jungle Weaver without significant help. There are very few removal spells that can actually kill Jungle Weaver. And when it attacks, it packs quite the punch.

Consider the fact it does have cycling and you have a card that is always going to be fine, and is excellent if the game goes late. When I play with one of these seven-cost creatures I usually play it about half of the time and cycle it the other half (though admittedly, I'll wait a little bit longer to be able to play Jungle Weaver than I would the others).

Otherwise Unplayable

Savage Hunger is very rarely worth playing. But, if you do play it, that's great! That probably means that you are going to win that turn. If you play it and you don't win that turn (or at least connecting for a lot of damage) then it probably means that your opponent had something really good, or you shouldn't have played Savage Hunger in the first place.

Like Savage Hunger, Spell Snip is a great card to snip from your deck. Yes, it cycles, so you'll never be too upset to have to play it, but the times where you will be able to counter something relevant with Spell Snip are few and far between.

Resounding

If you cycle one of the Resounding spells, then you're going to feel pretty good about yourself. But let's take a look at how the Resounding spells stack up depending on whether or not your deck will be able to use them to their fullest.

Resounding Thunder is always going to be excellent, so I don't need to waste your time talking about it.

Verdict:

Cycleable = excellent

Never cycleable = excellent

Resounding Silence is reasonable if you have no chance of cycling it, but it isn't spectacular. It's generally pretty easy to spot a player who is trying to play Resounding Silence early on or midway through the game ("Gee, you just played your sixth land and a 2 drop and you didn't play anything last turn. I wonder what you could possibly have...."), but later on it becomes harder to spot. For that reason, amongst many others, I'm (obviously) much happier to play Resounding Silence in a deck that can cycle it than in one that can't. I rarely play Resounding Silence until I have 6+ mana sources anyway, so it's really a shame to play it when I'm not going to get a chance to really profit from it.

If I can cycle it, I have no problem taking Resounding Silence pretty early in the draft. But if I can't, then I'm probably not going to be looking to pick it up until about fifth or sixth pick.

Verdict:

Cycleable = very good

Never Cycleable = OK to good

Resounding Wave really just doesn't do it for me if I can't cycle it. I'll play it in non-Esper decks sometimes, but if I can't cycle it then I'm going to be pretty reluctant to include this three-mana Boomerang. Even if I can cycle it, I wouldn't want to draft a Resounding Wave before about sixth or seventh pick.

Verdict:

Cycleable = good

Never Cycleable = OK

Resounding Roar is an obviously good card, but it is rarely great. I'll play it in pretty much any green deck, and I'm pretty happy when I can cycle it. Not being able to cycle Resounding Roar won't significantly affect how I draft it, but it's certainly a big plus to be able to cycle it for a BIG PLUS. Cycleable or no, I feel fine picking up a Resounding Roar from around fourth pick on.

Verdict:

Cycleable = good to very good

Never Cycleable = good

"Resounding Scream, yick." It's not quite that bad, if you're playing a slow Obelisk-heavy deck against another slow deck then you are going to want to have a Resounding Scream on hand. But other than that, Resounding Scream probably doesn't have a place anywhere in your 40 cards.

Verdict:

Cycleable = OK

Never Cycleable = bad

Wait, It Has Cycling?

Unlike most of the other cycling cards in the set, Viscera Dragger is not a card that I look to cycle. There are certainly times when I don't have a black source, I'm in danger of missing land drops, or I need to dig for a key card, and I'm going to cycle Viscera Dragger, but most of the time I just want to play my unearthable hill giant.

Flexibility is what makes OK cards good and good cards great. Some cards, such as cheap removal spells like Magma Spray, offer a TON of flexibility just because of what they do. But other cards need to have alternative ways to be played to achieve that level of flexibility. Cycling does this.

For many of the cycling cards in the set, if you cycle them, you're getting a smaller ability than the one that you would get if you played them. Of course, the opposite is true with the Resounding cycle.

But regardless of which way is the most powerful way to use your cycling card, having the ability use play a card in two different ways, one of which is OK to good early, and the other of which is OK to good late, means that you're probably looking at a card that's worth playing.

Bonus Exercise

You've just finished drafting and building your deck in the Top 8 of a PTQ and this is what you've got.